The present invention relates to a method as set forth in the preamble of claim 1 for removing a propeller assembly from and for mounting the same in an opening in the bottom of a swimming vessel as well as to an apparatus as set forth in the preamble of claim 4.
An object of the present invention is to provide an improved and relatively simple and reliable method and apparatus for removing and mounting a propeller assembly for maintenance, repairs or replacement without having to bring the vessel to dock. This is particularly important in connection with various rig platforms used by off-shore industry, said rigs being often designed to remain stationary for long periods of time, e.g. up to 20 years. In the prior art, the propeller assemblies have been installed and removed from outside the vessel by means of various hoisting mechanisms. In a normal case, these necessitate the use of a diver for securing the hoisting cables to the propeller assembly. A drawback in such externally performed removal and installation of a propeller assembly is that such operations are highly dependent on weather conditions. In poor weather, a diver cannot be used for such operations for reasons of safety.
In order to achieve the above-described object of invention, a method of the invention is characterized by what is set forth in the characterizing clause of claim 1. On the other hand, an apparatus of the invention is characterized by what is set forth in the characterizing clause of claim 4.